I don't think it is actually Earth Day, but San Diego had its hugemongous EarthFair in Balboa Park. It is billed as the "largest free annual environmental fair in the world". So I figure it offers a good excuse to comment on environmentalism.
Personally I think of environmentalism, by which I mean an idea that the preservation of a 'natural' environment ought to be one of the highest priorities, as a little bit like the Atkins diet. Both have useful insights which can make daily life much better, but both have quite a few followers who take things way too far.
I don't believe that there is any reason why conservatives ought to be anti-environment or even indifferent to the environment. We ought to respect the fact that human beings alter environments and like many complex systems the effects may not be obvious or direct. Conservatives are aware of this possibility in complex human interactions, and should be willing to extend the train of thought to complex environmental systems. That said, I don't believe that environmental purity (which I take to mean as the state of the environment if human beings didn't exist or did not effect an environment) is a particularly worthy goal for government involvement.
A better goal would be to reduce human impact while allowing human beings to do most of the things that they do. Take notions of clean air for instance. I think everyone can agree that air quality ought to be better than is found in Mexico City. And lots of improvements can be made. The catalytic converter offers a dramatic reduction in emissions for a moderate (thought not inexpensive) cost. As a result, LA has dramatically reduced smog levels (dramatically reduced not eliminated), while Sydney is still smog-infested. The problem comes when you fail to factor in diminishing returns. Trying to reduce smog levels by an additional 60% or 70% isn't going to come at the same moderate price. Like losing weight, making it most of the way to your target weight may be difficult, but it is no where near as difficult as the last couple of pounds. There are carcinogens which are already occur at such small levels that attempting to restrict them further is an exercise in throwing money away. For instance why all the fuss about arsenic when we aren't even dealing with lead paint effectively? We could spend hundreds of millions of dollars on reducing the arsenic levels and not impact as many lives as a couple of thousand dollars spent dealing with lead paint in one house.
The key insight of the environmental movement is that individual actions which are not a big deal of themselves can combine in large human groups to create a large problem. One person dumping a chamber pot into the ocean makes a negligible difference, but having all of Tijuana dump sewage into the ocean can cause problems as far away as Los Angeles.
The old environmental movement had a very conservative-like slogan: "Think Globally, Act Locally". It is a slogan which I entirely agree with. It turns the above insight into a method of correcting problems. There are probably 10-20 small choices that you make each day which if made by a large segment of society on a regular basis could make quite a difference. As an example, when purchasing one or two items at a store, decline to take a bag. You are just going to throw it away 1 second after you get home. Why use it at all? When purchasing your car, you could ask yourself "Am I going to use this for off-roading? Do I live in an area with heavy snow?". If the answers are 'no', you probably could avoid 4-wheel drive. You could turn off lights when you aren't in the room (why is my roommate glaring at me?). When going to dinner with nearby friends you could pick them up in your car instead of having everyone meet at the restaurant. You could use e-mail more frequently than mailed letters. You could make archived records on disc instead of printing out everything.
I think that if we put our minds to it, conservatives could come up with an excellent environmental ideology which is non-absolutist. It would contain elements of social pressure, an awareness of diminishing returns (especially in government action) and a willingness to really balance costs and benefits (as opposed to pretending to balance them while trying to allow a company to do whatever it wants). I'm not going to try to claim that I have actually done so in the above post, but I think it provides the kernel of thought for such a plan.